Washington -LRB- CNN -RRB- -- Congressional negotiators reached a tentative deal Tuesday to extend the payroll tax cut and unemployment benefits while avoiding a fee cut for Medicare doctors , according to Republican legislators and aides .

The framework deal followed a key Republican concession Monday and could receive the endorsement of a House-Senate conference committee on Wednesday .

Reps. Renee Ellmers of North Carolina and Fred Upton of Michigan , both Republicans who were part of the conference committee negotiations , called it a tentative agreement , while a top House Democratic aide said Democratic leaders would discuss the proposal with their members on Wednesday morning .

Ellmers and Upton said they expected the conference committee to sign off on the measure Wednesday if no objections arise . In that case , the House would vote on the agreement , in the form of the conference committee report , as soon as Friday .

However , some conservative House Republicans expressed concerns about the potential agreement and said they were unsure if they would support it . Other GOP House legislators said they expected it to pass with support from a majority of Republicans , as well as Democrats .

`` It 's the art of a deal . I mean , it 's a compromise , '' said Rep. Steve Latourette , R-Ohio . `` So you have people that did n't get a 100 % of what they wanted . ''

Under the agreement that would cover the rest of 2012 , the nearly $ 100 billion payroll tax cut would not be paid for -- a consequence of the parties ' inability to compromise on either new taxes or offsetting spending cuts , said top congressional aides from both parties .

It would be coupled , however , with measures extending unemployment benefits and preventing a fee cut to Medicare doctors -- known in Washington as the `` doc fix . '' The latter two measures -- costing a combined $ 50 billion -- would be paid for , the aides said .

Possible funding sources to pay for the measure include saving from broadband spectrum sales of about $ 13 billion , increased pension contributions by federal employees of about $ 16 billion and cuts to Medicare hospital and specialist fees that would not impact patients , according to the congressional aides .

`` I think they have to work out all the details , but I think the big scope has been agreed to , '' House Speaker John Boehner , R-Ohio , told reporters . However , House Majority Leader Eric Cantor , R-Virginia , was less enthusiastic , saying `` this is not our preferred way '' to deal with the issues and adding that details were still being studied .

Congressional aides differed by party on details of extending the unemployment benefits , particularly the maximum number of weeks that will be funded . While a Democratic aide said the maximum for states with high unemployment would continue at the current 99 weeks , a Republican aide said the maximum would be 89 weeks and most states would have a maximum of 63 weeks of benefits by the end of the year .

Some Republicans wanted unemployed individuals to pass drug tests and meet certain education standards before getting benefits -- an idea generally opposed by Democrats . A top Republican aide said the tentative agreement would allow for states to conduct drug testing when the unemployment benefits applicant was seeking a job that required drug testing or lost a job due to a failed drug test .

News of the tentative deal came hours after President Barack Obama publicly urged Congress to extend the payroll tax cut , which is currently set to expire at the end of February . Failure to do so , Obama warned , could derail the economic recovery .

`` This is a make-or-break moment for the middle class , '' the president said . `` The last thing we need is for Washington to stand in the way of America 's comeback . ''

White House Press Secretary Jay Carney later told reporters that the payroll tax cut , extension of unemployment benefits and `` doc fix '' provision all were `` important to the economy in different ways . ''

`` It is of vital importance that Congress not muck up the recovery that we 're seeing under way , '' Carney said of the need for a broad agreement .

The payroll tax cut , unemployment benefits and enhanced `` doc fix '' payments are set to expire at the end of February under a short-term agreement reached by Congress in December . That agreement also set up the conference committee that resumed negotiations last month on a longer-term deal .

Final negotiations have been hammered out by the two committee chairman , Democratic Sen. Max Baucus of Montana and Republican Rep. Dave Camp of Michigan , in conjunction with Senate Majority Leader Harry Reid , D-Nevada , and Boehner .

The payroll tax cut , a key part of Obama 's economic recovery plan , has reduced how much 160 million American workers pay into Social Security on their first $ 110,100 in wages . Instead of paying in 6.2 % , they 've been paying 4.2 % for the past year and two months . The break is worth about $ 83 a month for someone making $ 50,000 .

On Monday , House GOP leaders dropped their demand that any extension of the tax cut be offset by spending cuts elsewhere in the budget . The decision was a sharp turnaround for House Republicans , who previously argued that a failure to fully pay for the tax break would be financially reckless .

The debate over whether and how to extend the tax cut has been a political loser so far for the Republicans , who had publicly questioned its value last year . Democrats have gleefully highlighted the GOP 's reluctance , using the issue to portray Republicans as defenders of the rich who are indifferent to the plight of the middle class .

Political analysts believe the showdown over the payroll holiday has eroded GOP strength on the party 's core issue of lower taxes . Fearing negative repercussions , Republican leaders have now backtracked on the issue twice : dropping their opposition to the two-month extension last December and dropping their insistence on paying for a longer extension on Monday .

`` I think the GOP has read the writing on the wall when it comes to the payroll tax cut , '' said Brown University political scientist Wendy Schiller . `` Americans are benefiting from it , and to take it away at this juncture leaves them open to charges of raising taxes . ... It would severely hamper the GOP presidential nominee 's effort to defeat Obama . ''

Johns Hopkins University political scientist Adam Sheingate called the GOP 's latest move `` a subtle shift in strategy precipitated by the improving economic outlook of the past few weeks . ''

`` By agreeing to a deal , the GOP can claim some credit for extending the holiday , '' Sheingate said . `` Failing to extend the payroll tax would not only be unpopular , it would shift some of the responsibility for the economy back on the Republicans . This is to be avoided at all costs since the GOP -LRB- election -RRB- strategy rests almost entirely on Obama 's handling of the economy . ''

In announcing their shift on the payroll tax issue Monday , Boehner and two other top House GOP leaders said they wanted separate the matter from legislation dealing with unemployment benefits and the doc fix .

Doing so would `` protect small businesses and our economy from the consequences of Washington Democrats ' political games , '' said Boehner , Cantor and House Majority Whip Kevin McCarthy , R-California .

Schiller told CNN the idea of divorcing the payroll tax cut from an unemployment benefits extension and the doc fix was a `` clever '' idea on the part of the House GOP leadership .

Doing so would have removed the Democrats ' `` leverage on the other issues of unemployment and Medicare payments , '' she said . `` Also , as the unemployment numbers get better , the rationale for a lengthy extension of benefits diminishes . The longer the GOP can stall on the unemployment extension , the more likely it is they win in terms of authorizing a much shorter extension than the Democrats would like . ''

Democrats , however , quickly pushed back hard against the idea .

Senate Majority Leader Harry Reid , D-Nevada , and House Minority Leader Nancy Pelosi , D-California , on Tuesday urged Republicans to allow Congress to quickly complete its work on all three issues -- the payroll tax cut , unemployment insurance , and the doc fix .

Pelosi said Congress should cancel a recess currently scheduled for next week if it fails to complete work on all of them by Friday .

`` These crucial policies affect millions of middle class families and seniors and must not expire at the end of this month , '' Pelosi said .

Instead of a separate measure involving only the payroll tax cut extension , the tentative agreement Tuesday was a more comprehensive package worked out by the conference committee negotiators

It remains unclear if the increasingly conservative House GOP caucus will be willing to go along with the tentative deal . House Republican freshmen , elected on a tidal wave of tea party support in 2010 , have made deficit reduction their top priority and repeatedly insisted that any new initiatives be fully paid for .

Rep. Dennis Ross , R-Florida , said discussion Tuesday night in the House Republican caucus was `` heated '' over not paying for the payroll tax cut extension , which he called `` bad policy , '' while fellow Floridian Rep. Allen West , a tea party conservative , said `` this does n't look like a good deal to me . ''

Meanwhile , two New York Republicans , Reps. Tom Reed and Peter King , sounded more supportive , with King saying he expected the measure to pass .

One key conservative , Rep. Jim Jordan of Ohio , indicated Tuesday he 's prepared to back Boehner and the other House GOP leaders .

Jordan 's `` view is anytime we 're letting people keep more of their money , that 's a good thing , '' said Brian Straessle , a spokesman for the Republican congressman .

Veteran political analyst Norm Ornstein warned that the GOP leadership 's repeated maneuvering on the issue could end up backfiring .

House Republican leaders have been `` trying to make the best of crummy situation , '' Ornstein told CNN . But tea party Republicans `` do n't care '' if fighting the tax cut extension is `` a political loser . They do n't like the payroll tax cut and now the -LRB- leadership 's -RRB- sin is being compounded by saying they wo n't pay for it . ''

This `` could play out in ways that make the life of Boehner -LRB- and other Republican leaders -RRB- a little less comfortable , '' he predicted .

CNNMoney 's Jeanne Sahadi and CNN 's Tom Cohen and Rebecca Stewart contributed to this report

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NEW : Some Republican congressmen question the tentative agreement

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Progress is made after Republicans back down on payroll tax cut

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Political analyst Norm Ornstein warns new GOP strategy could backfire

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President Obama warns that failing to act could hurt the economic recovery